The industrial use of MMMF(man-made mineral fibers), has been increasing, particularly since the banning of most asbestos products. Fibrous minerals can cause health abnormalities currently associated with occupational exposure to glass fiber. This study was conducted to evaluate health risks of glass fiber manufactory workers within the country. We examined questionaries, physical examination including auscultation, chest x-ray, pulmonary function test for 488 male workers, to go through their dermal itching symptoms and respiratory evaluation. we had the results as follows. 1. In 45% of the workers itching had been expressed at their entrance. At that time we was investigating, 18.5% had itching, and most of them complained it when they fall asleep and night. The Sequent itching site is waist and groin, upper and lower extremity in order, and it had been expressed mainly during summer and winter. 2. As the results of ventilatory functions test, 6.0% were obstructive type, 1.0% were restrictive type. So, glass fiber exposures should be controlled or elimination by protective devices in the workplace. 3. The means of FVC, $FEV_1,;FEV_1%$ were in normal range. As the comparison of ventilatory functions by age groups, MMF was decreased significantly for the group, 50 years old and more than other groups. And the comparison by the serving periods at glass fiber producing factory, MMF was decreased for the workers had worked for $11sim15$ years. Therefore, MMF be more sensitive index in the evaluation of ventilatory impairments caused by glass fiber workers.